Almon w



A. W. COPLEY.

MEANS FOR MlNlMlZlNG INDUCTIVE INTERFERENCE.

' APPLICATION mm NOV-3.1917

1,318,730. I Patented Oct. 14,1919.

WITNESSES: INVENTOR Elma/1 W Copley.

W M g g Q ATTORNEY UNITED STATES PATENT OFFICE.

ALMON w. COPLEY, or Williams-Bone,rnnNsYrvAnm, Assrenon" mo WESTINGHOUSE.

nrno'rmc & MANUFACTURING com-zany, A GOBPORATION orrEnnsYLvAnIA.

unansron ummlzire m njeai nmranraswda T all wh m. t oncer Be it kn wn t at I, ALMQ m n a citizenof the United States, and a res1- e t. of Wi kinshurg, n th coun y of All ghenyand State ofPenn yl e a h ented a and useful Impr e 111 Means, 'ifor Minimizil Indu ti e Interfer tion." My invention relates to means for minimizing inductive disturbances that may be impressed by an alternating-current transm ssion system upon an adjacent electrical c rcu t such as an 'll'ltQlllgGIlCG-tIMISIHlSSlOII circuit, Y

More particularly, iny'invention relates V to means whereby inductive disturbances,

arising from the flow of currents in' an alter nating-current railway system and tending to impair the transmission of intelligence over an adjacent telephoneor telegraph 'c1'rcnit, may be substantially minimized.

In U. S, Patent No. 1,196,300, means are shown for confining the'returnflow oi. the trolley currents of railway system to the track rails or in' regions ofthe earth that are closely adjacent tothe track rails. In-

this manner, the zones of disturbing influences arising fromthereturn fiowof the power currents are restrictedto limitedregions relatively close tothe trolley conductors where'the former may be used efiec; tively to neutralize the disturbances occasioned b the latter. By thus confining the current liow to the'track rails,jinductive disturbances to which other electrical circuits are subjected, such as intelligence-transmission circuits that are located in proximity to'the'railway system, may beg-reatlymini mized or substantially neutralized. w

The, system shown in the aforementioned patent contemplates the-use of series trans formers having primary windings that are connected in series circuit with the trolley conductor and secondary windings that are adapted toconnect adjacent trackfseotions in series relationship with one another, In this manner,- the trolley conductor and the trackjrails are inductivelyinterlinked with each other and, by reason of the inherent action of these series transformers, the return flow oi the trolleycurrents is confined to the track rails. a a

The arrangementmentioned above is,

however, ineffective in protecting anadja- 1 Patented Oct. 14, 19.19. App ca fil d Nmmw 3,1313 sat-aim a aoas, I

cent electrical circuit, such as a telephone power currentswill be confined to the track rails, undernoimal conditions. The feeder mains are likewise inductively interlinked with the track rails in order to preclude the generat onof serious inductive disturbances whenl'a ground is imposed upon the feeder circuit.

For a bGtte'r understanding o f the char-- acteristic features of my lnvention, refer ence may be had to; the following descrip-' tlon and the accompanyingdrawing, thesinglerfigure of which is a schematic diagramofasystem" embodying a form of my Invention, '1,

Referring to the figure, feeder mains 1 and 2 parallel a railway system 3 to which power is supplied by means of transformers 4- and 5 that are located at conveniently spaced sub-stations '6 and 6, respectively.

A"power transformer that is located at the generating station supplies high-potem tialicurrent to the feeders 1 and 2. r The secondary winding 8iof the transformer 7 is provided with an intermediate tan 9 that is grounded at 10 a The secondarywindings 11 and '12 of the transformers 4and 5 have their corresponding terminals connected to.

a trolley conductor 13 and track rails id of the railwaysystem 3. a i The trac'krails 14 are divided into sections by means of; spaced insulating joints 15 and are connected to one another by means of metallic bonds 16'. A plurality of transformers 1'71 are inserted at intervals along the railway system, as shown, and coniprise primary'windings 18 that are connected in series-circuit relationship with the trolley conductor 13 and secondary windings 19 that are connected to the rails 14: through the conducting bonds 16 and across the insulating joints 15. i i

Other windings 20 and 21 areincorporated in the transformers 17, the former being' connectedin series-circuit relationship with the feeder main 2 andthd latter being similarly connected to the feeder main 1. The windings 18, 19, 20 and 21 of each transformer may be disposed upon a single core member, the windings 20 and 21 being so wound that, under normal conditions, the magnetic fluxes arising therefrom will substantially neutralize each other. This is readily accomplished since the direction of current flow in the main 1 is opposite to the direction of current flow in the main 2, under normal conditions. Similarly, the direction of current flow in the winding 18 is opposite tothe direction of current flow in the winding 19.

As a result of inductively interlinking the trolley conductor 13 with the track rails 14, the current flow in the earth will, in general, be for short distances only. The windings 18 and 19 will usually, though not always, comprise substantially equal numbers of turns and, therefore, by reason of the necessity of the ampere turns in the primary winding 18 being nearly equal to the ampere turns in the secondary winding 19, the return flow of the trolley currents will be ordinarily confined to the track rails 14 which are disposed in proximity to the trolley conductor 13. In consequence thereof, the induc tive disturbances that may be imposed upon an adjacent circuit 22, shown as a telephone circuit, will be substantially neutralized.

The current flow in the feeder circuit will usually occasion inappreciable disturbances in the telephone circuit 22, since the feeder mains 1 and 2 are thoroughly insulated from ground and the current flow over one is in a direction opposite to that over the other. As a result, the inductive ef fects arising from the current flow over one of the mains will be neutralized by the inductive effects arising from the oppositelydirected current flow in the other main.

Assumed, for the purpose of illustration only, that a ground 23 is imposed upon the main 1. If the main 1 were not inductively interlinked with the track rails 14 through the transformers 17 the ground currents arising from the grounded connection 23 would seriously interfere with the proper operation of the intelligence-transmission circuit 22. But, since the feeder mains 1 and 2 are severally inductively interlinked with the track rails 14, through the transformers 17 these ground currents are precluded from flowing any appreciable distance through the earth but will, of necessity, traverse the track rails 14.

Because of the return flow of these currents being confined to the track rails 14, in preference to the earth, the inductive disturbances that may& be impressed upon the telephone circuit 22 are not of a serious character. Under this condition, the windings21 serve as primary windings of the series transformers 17 and the windings 15) as secondary windings. Therefore, the

series transformers 17 serve to inductively interlink the feeder mains 1 and 2 with the track rails 14 when a ground is imposed on the feeder circuit. Since the several transformer windings 18, 19, 20 and 21 are presumed to have substantially the same number of turns, the current traversing the track rails 14 will be substantially equal to the current traversing the feeder main 1 and the grounded connection 23. The resultant inductive disturbance that may be imposed upon the telephone conductor 22 will therefore be negligible. 1

WVhile I have shown and described one embodiment only of my invention, it will be understood that many modifications may be made therein without departing from the spirit and scope of the appended claims.

I claim as my invention:

1. The combination with a feeder circuit, and a power circuit one conductor of which is in contact with the earth, of a plurality of spaced transformers for inductively interlinking the conductors of said feeder circuit and the other conductor of the power circuit with said conductor of the power circuit that is in contact with the earth.

2. The combination with a feeder circuit, a railway system comprising a trolley conductor for the transmission of power currents and a track, and means for transferring power currents to the railway system from the feeder circuit, of means for inductively interlinking said track with the trolley conductor and the conductors of said feeder circuit at spaced intervals.

. 3. The combination with a feeder circuit, and a railway system comprising a trolley conductor for the transmission of power currents and a track, of transformers for inductively interlinking the trolley conductor and the conductors of said feeder circuit with said track at spaced intervals.

4. The combination with a feeder circuit, and a railway system comprising a trolley conductor for the transmission of power currents and a track, of spaced transformers having windings that are severally connected in series circuit with the conductors of said feeder circuit and the railway system in order to inductively interlink the conductors thereof with one another. 7

5. The combination with an intelligencetransmission conductor, of an electrical distributing system in inductive relation thereto that comprises a feeder circuit having conductors insulated from ground, a power circuit which comprises a conductor insulated from ground and a second conductor in contact with the earth, and inductively interlinking means serving to confine the ground currents from both of said circuits to said second conductor of the power circuit in preference to the earth, whereby the inductive effects impressed upon conductor with said track in order that the return flow of the trolley currents, as Well as ground currents from the feeder circuit, may be confined to said track in preference to the earth.

In testimony whereof, I have hereunto subscribed my name this 23rd day of Oct., 191

the said intelligence-transmission conductor may be substantially neutralized.

6. The combination With an intelligencetransmission conductor, of a feeder circuit, 5 a railway circuit, both of which are inductively related to said inte1ligencetransmission conductor, said railway circuit comprising a trolley conductor and a track, and means for inductively interlinking the conv 10 ductors of said feeder circuit and the trolley ALMON W. COPLEY.

copies of this patent may be obtained for five cents each, by addressing the Commissioner of Patents, Washington, D. G. 

